System and method for controlling abrasive flow in a pneumatic blasting system

The present disclosure relates to a system and method for controlling abrasive flow through a pneumatic blasting apparatus.

Any references to methods, apparatus or documents of the prior art or related art are not to be taken as constituting any evidence or admission that they formed, or form, part of the common general knowledge.

It is known to provide a blasting apparatus in which particles of abrasive material entrained in a stream of pressurised gas, most usually air, are expelled from a nozzle in a high velocity jet of the air that is directed onto a surface in order that the particles forcibly impact the surface to clean and/or abrade the surface.

One commonly used abrasive material is sand, and when sand is used the blasting process may be referred to as sand blasting. However, other abrasive materials may be used, such as garnet.

1 FIG. 10 26 20 10 24 10 28 10 14 16 12 16 shows a known electrically activated blast pot arrangement. The blast potcontains an abrasive material and is capable of being pressurised (via the compressed air inlet) to an optimal pressure required for the blasting process—typically 80 to 120 psi. A depressurisation valveprovides a mechanism to depressurise the blast pot, and a pressure relief valverestricts the high pressure to 150 psi. The blast potcan have a single abrasive outlet port or multiple abrasive outlet ports. A moisture separatorremoves moisture from the airstream before it enters the blast pot. An abrasive flow metering valvecouples the blast pot abrasive outlet port and a blast hosethrough which the abrasive media, mixed with compressed air from the pusher lineflows. This abrasive material and air mixture moves through the blast hoseto the hose outlet where it passes through an abrasive blasting nozzle (not shown) and is directed onto the work surface to be treated.

14 10 16 14 18 22 16 The abrasive flow metering valveis adjustable to control the flow of abrasive material from the blast potinto the blast hose. The abrasive metering valveis typically manually adjusted to control flow of abrasive material. A deadman handle (not shown) activates/deactivates a control valvewhich in turn activates/deactivates an auto air valveresulting in pressurised air flow being supplied to or cut off to the blast hose.

18 The operation of the control valvecan be via either pneumatic or electrical means.

22 12 16 14 16 An auto air valve, or solenoid valveon the pusher linemay be used to shut off pressurised air supply to the blast hosethereby creating a choking effect to force any blockages in the abrasive metering valveout and into the blast hose.

Various blasting hardware configurations can be used with the pneumatic blasting system. This includes but is not limited to different sized abrasive blasting nozzles, blast hose diameters commonly in use in the industry and other activation and control devices known to those skilled in the art.

In order to minimise the use of resources and reduce the time to complete surface preparation processes, it is preferable to optimise the operation of the abrasive blasting process. Factors such as type of abrasive material, size of the blast nozzle, blast hose pressure and abrasive flow rate are critical to optimising the abrasive blasting process. It is accepted that the optimal abrasive flow rate for the abrasive blasting process is different depending on the type of abrasive material and the size of the blast nozzle being used. It is also accepted that the optimal air pressure for abrasive blasting is typically 100 psi. An obstacle to optimising the blasting process is that blasting operators have varying levels of experience and may not have the ability to set the abrasive flow rate to the optimal rate or they may choose not to set the abrasive flow rate to the optimal level. Blasting operators may also not set the blasting air pressure to the optimum pressure.

14 10 14 In traditional systems the abrasive flow rate is manually set by the operator by trial and error and, for the reasons outlined above may result in a less than optimal ratio of abrasive material to air being used, for example the operator may visually inspect the air and abrasive mixture issuing from the nozzle An optimal air/abrasive mixture will be only slightly visible in the stream from the nozzle and will appear as a coloured haze. This adjustment is typically affected by the operator stopping the blasting process, moving from the location where the blasting is being carried out to the abrasive metering valvelocated underneath the blast pot, adjusting the abrasive metering value by an estimated amount, and then returning to the blasting location to recommence blasting and test if the adjustment resulted in the correct flow rate of abrasive. Whilst this adjustment of the abrasive metering valvecan also be done by a blast pot attendant or other assistant, thus eliminating travel time between locations, the adjustment is still reliant on operator judgement.

It has been known to manually adjust the rate of abrasive flow using control switches mounted near to the blasting nozzle. However, these remote manual adjustment methods continue to rely on operator judgement of the correct flow rate of abrasive material for the specific abrasive type and blasting nozzle size combination being used and only overcome the inconvenience of the operator having to stop blasting while the abrasive flow is adjusted on the abrasive metering valve at the location of the blast pot. Whilst various abrasive metering valve configurations and methods for actuating the abrasive metering valve can be used, these methods continue to rely on operator judgement. As a result, the flow rate of abrasive material is often not optimised for the abrasive type and nozzle size combination being used and results in the abrasive blasting process consuming more than the optimal amount of abrasive material and/or taking more time to complete.

It is an object of the present invention to provide a system and method for optimising abrasive flow in a pneumatic blasting apparatus, or to at least address one or more of the drawbacks discussed above.

In one aspect there is provided a system and method for automatically controlling abrasive flow through a blast hose by storing operational data, converting the data into user operational information, displaying the information on a user interface display screen, and communicating with remote devices via a compatible wireless mobile network to display and select system parameters.

an abrasive flow sensor for measuring abrasive flowrate through the at least one blast hose; an abrasive metering valve for controlling abrasive flowrate through the at least one blast hose; anda controller configured to receive a signal from the abrasive flow sensor and actuate the abrasive metering valve based on a set of conditions, the set of conditions including an optimum abrasive flow rate range having an upper limit and a lower limit, and wherein the controller is configured to determine the optimum abrasive flow rate range based on a combination of nozzle size and abrasive type. In an aspect of the present invention there is provided an automated abrasive control system for controlling abrasive flow in a pneumatic abrasive blast pot arrangement having at least one blast hose, the control system including:

A. Auto—The controller is configured to optimise the use of abrasive during the blasting process by automatically adjusting the abrasive flow rate to remain within the optimum abrasive flow rate range for the nozzle size and abrasive type combination in use. B. Semi-Auto—The controller is configured to adjust the abrasive usage to a flow rate set by the operator. C. Manual—The controller is configured to allow the operator to manually set an abrasive flow rate. In an embodiment, the controller is configured to operate in three Modes:

In an embodiment the controller is configured to continuously receive the signal from the abrasive flow sensor and actuate the abrasive metering valve. In an embodiment the controller is configured to continuously receive the signal from the abrasive flow sensor at a predetermined frequency to allow the abrasive control system to stabilise after the abrasive metering valve has been actuated.

In an embodiment an emergency stop button is included, configured to shut off the compressed air entering the pot when activated.

In an embodiment the controller is configured to compare the measured, or actual abrasive flow rate sensed by the abrasive flow sensor with a predetermined optimum flow rate range for the selected nozzle size and abrasive type combination. The controller is configured to increase flow of abrasive by actuating, or opening, the abrasive metering valve if the actual flow of abrasive sensed is lower than the lower limit of the predetermined optimum flow rate range of abrasive flow for the selected nozzle size and abrasive type combination. If the actual flow of abrasive sensed is higher than the higher limit of the predetermined optimum flow rate range of abrasive flow for the selected nozzle size and abrasive type combination, the controller is configured to reduce flow of abrasive by actuating, or closing, the abrasive metering valve.

In an embodiment, the abrasive metering valve opens or closes based on a differential between the actual flow rate and the predetermined optimum flow rate.

In a preferred embodiment the automated abrasive control system includes a user interface display screen in communication with the controller and configured to display actual instantaneous system operating parameters and operating trends.

In an embodiment, the control system is configured to select and update the system operating parameters and settings from a remote location via electronic devices wirelessly connected to the controller.

In an embodiment, the controller is configured to compare the measured abrasive flow rate sensed by the abrasive flow sensor with the optimum abrasive flow rate range, and if the measured flow rate is outside the optimum abrasive flow rate range the controller actuates the abrasive metering valve to either open or close until the measured abrasive flow rate is within the optimum abrasive flow rate range.

In an embodiment, the controller is configured to open the abrasive metering valve if the measured abrasive flow rate is lower than the lower limit of the optimum abrasive flow rate range for the selected nozzle size and abrasive type combination and close the abrasive metering valve if the measured abrasive flow rate is higher than the higher limit of the optimum abrasive flow rate range for the selected nozzle size and abrasive type combination.

In an embodiment, the automated control system includes a solenoid, or auto air valve for controlling air flow to the blast hose, and wherein when the measured abrasive flow rate is lower than the lower limit of the optimum abrasive flow rate range for a predetermined amount of time, for example, in the case of a blockage in the abrasive metering valve, the controller is configured to actuate the solenoid valve repeatedly several times to promote a higher pressure in the blast pot than in the blast hose when the solenoid valve is closed to remove blockages from the abrasive metering valve or blast hose. This is operation is referred to as choking.

In one embodiment at least one blast pot includes a plurality of blast hoses, each with a respective abrasive flow rate sensor and abrasive metering valve, and the controller is configured to independently monitor flow rate signals from each abrasive flow rate sensor and to independently actuate each respective abrasive metering valve based on the set of predetermined conditions.

In an embodiment, the controller is configured to selectively provide a plurality of abrasive blasting nozzle sizes to be used during blasting operations. In an embodiment, the controller is configured to selectively provide a plurality of abrasive types to be used during blasting operations, and the controller is configured to provide the optimum abrasive flow rate range for the selected nozzle size and abrasive type combination.

a plurality of sensors configured to measure system operating parameters; a controller in communication with the plurality of sensors and configured to store the measured system operating parameters; and a user interface display screen in communication with the controller and configured to display the system operating parameters. Another aspect of the present invention provides an automated control system for a pneumatic abrasive blast pot arrangement, the control system including:

In an embodiment the plurality of sensors includes an air pressure sensor connected to the controller, wherein the air pressure sensor measures air pressure of air entering the blast pot during operations (inlet pressure). The measured inlet pressure may be displayed on the user interface display screen. In an embodiment, the controller compares the actual, or measured inlet pressure with a predetermined optimal inlet pressure range, if the measured inlet pressure is outside the predetermined optimum range the controller is configured to trigger an inlet pressure alarm and display a warning on the user interface display screen.

In an embodiment, the plurality of sensors includes an air temperature sensor connected to the controller to measure air temperature of air entering the blast pot during operations (inlet temperature) and a dew point sensor connected to the controller to measure the dew point of air entering the blast pot during operations, wherein the controller is configured to display the measured, or actual, inlet temperature and the measured, or actual dew point, on the user interface display screen. In an embodiment, the controller is configured to compare the measured inlet temperature with the measured dew point, and if the inlet temperature is equal to dew point for a predetermined period of time the controller is configured to trigger a high air moisture content alarm and display a warning on the user interface display screen.

In an embodiment, the plurality of sensors includes a pressure transducer connected to the controller to measure air pressure in the blast hose and display the air pressure on the user interface display screen.

In an embodiment, the controller is configured to compare air pressure measured in the blast control line with a predetermined optimal pressure range, and if the measured pressure in the blast control line is outside the predetermined optimum range the controller is configured to trigger a hose high or low pressure alarm (depending on actual pressure in the hose) and display a warning on the user interface display screen.

In an embodiment, the plurality of sensors includes an air pressure sensor for measuring air pressure prior to the abrasive flow valve (pusher line), and the controller is configured to log when the air pressure prior to the abrasive flow valve (pusher line) is above a predetermined minimum pressure, indicating the blast hose is in operation.

In an embodiment the controller is configured to log data from the plurality of sensors for subsequent downloading to another computational device for in depth analysis and reporting. In an embodiment, information downloaded from the controller may be processed and displayed on the user interface display screen. In an embodiment, the user interface display screen may be positioned remote from the abrasive blasting pot.

In an embodiment, the plurality of sensors includes a Global Positioning System connected to the controller. In an embodiment, the controller is configured to log the location of the pneumatic abrasive blast pot during operation.

In an embodiment, the controller is configured to trigger an alarm if any of the measured system operating parameters is outside a predetermined range.

In an embodiment, the system operating parameters include air pressure entering the blast pot.

In an embodiment, the system operating parameters include air temperature entering the blast pot.

In an embodiment, the system operating parameters include dew point of air entering the blast pot.

In an embodiment, the controller is configured to compare the measured air temperature of air entering the blast pot with the measured dew point of air entering the blast pot, and if the measured air temperature is equal to the dew point for a predetermined period of time the controller is configured to trigger an alarm and display a warning on the user interface display screen.

providing a sensor for measuring abrasive flow rate through each of the at least one blast hose; providing an abrasive metering valve responsive to the sensor; providing a controller in communication with the sensor and the abrasive metering valve; inputting at least one predetermined optimum abrasive flow rate range having an upper limit and a lower limit, for a combination of nozzle size and abrasive type, into the controller; inputting a selected nozzle size and abrasive type combination into the controller, the controller being configured to determine an optimum abrasive flow rate range from the at least one predetermined optimum abrasive flow rate range based on the selected nozzle size and abrasive type combination; measuring the abrasive flow rate through the at least one blast hose to determine a measured abrasive flow rate; comparing using the controller, the measured abrasive flow rate with the optimum abrasive flow rate range; and if the measured flow rate is outside the optimum abrasive flow rate range actuating via the controller the abrasive metering valve to open or close the abrasive metering valve to thereby bring the measured flow rate within the optimum abrasive flow rate range. A further aspect of the present invention provides a method for automatically controlling abrasive flow in a pneumatic abrasive blast pot arrangement having at least one blast hose, the method including:

In an embodiment, if the measured flow rate is higher than the optimum abrasive flow rate upper limit the controller actuates the abrasive metering valve to close a predetermined amount.

In an embodiment, if the measured abrasive flow rate is lower than the optimum abrasive flow rate lower limit the controller actuates the abrasive metering valve to open a predetermined amount.

storing a predetermined time limit for the measured abrasive flow rate to be out of range in the controller; timing how long the measured abrasive flow rate is out of range; and signalling an alarm if the out of range time exceeds the predetermined time limit. In one embodiment the method includes the steps:

an abrasive flow sensor for measuring abrasive flow rate through the at least one blast hose; an abrasive metering valve for controlling the abrasive flowrate through the at least one blast hose; and a controller configured to receive a signal from the abrasive flow sensor and actuate the abrasive metering valve based on a set of conditions, the set of conditions including an optimum abrasive flow rate range having an upper limit and a lower limit. In a further aspect there is provided an automated abrasive control system for controlling abrasive flow in a pneumatic abrasive blast pot arrangement having at least one blast hose, the automated abrasive control system including:

In an embodiment the controller is configured to determine the optimum abrasive flow rate range based on a combination of nozzle size and abrasive type.

In an embodiment the controller is configured to compare an actual abrasive flow rate sensed by the abrasive flow sensor with the optimum abrasive flow rate range, and if the actual abrasive flow rate is outside the optimum abrasive flow rate range to actuate the abrasive metering valve to either open or close until the actual abrasive flow rate sensed by the abrasive flow sensor is within the optimum abrasive flow rate range.

In an embodiment the controller is configured to open the abrasive metering valve if the actual abrasive flow rate is lower than the lower limit of the optimum abrasive flow rate range and wherein the controller is configured to close the abrasive metering valve if the actual abrasive flow rate is higher than the upper limit of the optimum abrasive flow rate range.

In an embodiment the controller is configured to either open or close the abrasive metering valve based on a differential between the actual abrasive flow rate and the upper limit of the optimum abrasive flow rate range or the lower limit of the optimum abrasive flow rate range.

In an embodiment the at least one blast hose comprises a plurality of blast hoses, each with a respective abrasive flow rate sensor and an abrasive metering valve, and the controller is configured to independently monitor flow rate signals from each abrasive flow rate sensor and to independently actuate each respective abrasive metering valve.

In an embodiment the automated abrasive control system further includes a solenoid valve positioned on the at least one blast hose, wherein the controller is configured to send toggle signals to the solenoid valve if the abrasive flow rate is below the lower limit for a predetermined period, so that the solenoid valve closes and opens several times, promoting a higher pressure in the pneumatic abrasive blast pot arrangement than in the blast hose and forcing possible blockages in the abrasive metering valve out and into the blast hose.

In an embodiment the controller is configured to receive a signal from the abrasive flow sensor and trigger an alarm based on a set of predetermined conditions.

a plurality of sensors configured to measure system operating parameters, wherein the controller is responsive to the plurality of sensors; and a user interface display screen in communication with the controller wherein the controller is configured to operate the user interface display screen to display measured values of the system operating parameters. In an embodiment the automated abrasive control system includes:

In an embodiment the controller is configured to trigger an alarm if any of the measured system operating parameters are outside a predetermined range.

In an embodiment the system operating parameters include air pressure entering the pneumatic abrasive blast pot arrangement.

In an embodiment the system operating parameters include air temperature entering the pneumatic abrasive blast pot arrangement.

In an embodiment the system operating parameters include dew point of air entering the pneumatic abrasive blast pot arrangement.

In an embodiment the controller is configured to compare a measured air temperature of air entering the pneumatic abrasive blast pot arrangement with a measured dew point of air entering the pneumatic abrasive blast pot arrangement, and if the measured air temperature is equal to the dew point for a predetermined period of time the controller is configured to trigger an alarm and display a warning on the user interface display screen.

providing a sensor for measuring abrasive flow rate through each of the at least one blast hose; providing an abrasive metering valve responsive to the sensor; providing a controller in communication with the sensor and the abrasive metering valve; inputting at least one optimum abrasive flow rate range having an upper limit and a lower limit into the controller; measuring the abrasive flow rate through the at least one blast hose to determine a measured abrasive flow rate; comparing, using the controller, the measured abrasive flow rate with the optimum abrasive flow rate range; and if the measured flow rate is outside the optimum abrasive flow rate range actuating via the controller the abrasive metering valve to open or close the abrasive metering valve to thereby bring the measured flow rate within the optimum abrasive flow rate range. In a further aspect of the present invention there is provided a method for automatically controlling abrasive flow in a pneumatic abrasive blast pot arrangement having at least one blast hose, the method including:

In an embodiment the optimum abrasive flow rate range is based on nozzle size and abrasive type combination.

In an embodiment if the measured flow rate is higher than the upper limit of the optimum abrasive flow rate range the controller actuates the abrasive metering valve to close.

In an embodiment if the measured abrasive flow rate is lower than the lower limit of the optimum abrasive flow rate range then the controller actuates the abrasive metering valve to open.

storing a predetermined time limit for the measured abrasive flow rate to be out of range in the controller; timing how long the measured abrasive flow rate is out of range; and signalling an alarm if the measured abrasive flow rate is out of range for a time that exceeds the predetermined time limit. In an embodiment the method includes:

2 2 FIGS.A andB 100 110 116 115 110 show an automated abrasive control systemfor controlling abrasive flow in a pneumatic abrasive blast pothaving at least one blast hose(shown coupled to a blast nozzle) in accordance with an embodiment of the present invention. The pneumatic abrasive blast potis used for the cleaning and preparation of surfaces in readiness for the application of paint systems or other surface treatment processes. A plurality of sensors (described below) accurately measures values of the system operating parameters such as air pressure, temperature, humidity, and abrasive flow rate.

100 120 116 114 116 112 120 114 The automated abrasive control systemincludes an abrasive flow sensorfor measuring abrasive flow rate through the at least one blast hose, an abrasive metering valvefor controlling abrasive flow rate through the at least one blast hose, and a controllerconfigured to receive a signal from the abrasive flow sensorand actuate the abrasive metering valvebased on a set of predetermined conditions such as nozzle size and abrasive media and combinations thereof.

100 A range of abrasive media commonly used in the industry can be used with the automated abrasive control system. Different types of abrasive media have varying densities and flow characteristics and thus need to be considered differently in conjunction with blast nozzle size to provide an optimal abrasive flow rate.

1. hose outlet pressure 2. nozzle standoff distance from the workpiece 3. angle of inclination of the nozzle to the workpiece 4. velocity the nozzle moves across the workpiece 5. type of abrasive used 6. surface condition of the workpiece 7. abrasive flow rate through the nozzle outlet A scientifically repeatable method to determine the optimal abrasive flow rate for the selected abrasive type and nozzle size combination has been developed that makes use of an automated robotic blast cabinet to ensure input parameters can be held constant whilst varying the value of a single input parameter to determine the impact of varying that single input parameter on blasting performance. These parameters include:

This allowed the blasting performance of various combinations of input parameters to be tested under controllable conditions and the optimum abrasive flow rate for the nozzle size and abrasive type combination to be determined. The following input parameters were held constant during the determination of the optimal abrasive flow rate:

1. Hose outlet Pressure 100 psi 2. Nozzle standoff distance 600 mm 3. Angle of inclination 90 degrees 4. Nozzle velocity No. 6 Nozzle - 0.1 meters/second No. 7 Nozzle - 0.1 meters/second No. 8 Nozzle - 0.17 meters/second 5. Type of abrasive used GMA Garnet - new/unused SpeedBlast 6. Surface condition Powder coated - average coating thickness No. 6 Nozzle - 350 μm No. 7 Nozze - 338 μm No. 8 Nozzle - 266 μm

The abrasive flow rate was changed for each test and the blasting performance for that test was recorded.

1. Select the nozzle size and abrasive type combination for which the optimal abrasive flow rate is to be determined. 2. Set the input parameters to be held constant (as per above) on the robotic blast cabinet. 3. Set the abrasive flow rate to the minimum setting. 4. Blast a test strip at the minimum abrasive flow rate setting. 5. Measure the maximum width of the blast pattern on the workpiece that would be classed as a Class 3 prepared surface. 6. Incrementally increase the abrasive flow rate setting and blast a test strip at this setting. 7. Measure the maximum width of the blast pattern on the workpiece that would be classed as a Class 3 prepared surface. 8. Repeat steps 6 and 7 until the maximum abrasive setting is reached. 9. Compare the width of the blast patterns for each test strip and convert this into an area per hour cleaning rate. The optimum abrasive flow rate setting is the setting that produces the highest area/hour cleaning rate. 120 112 112 120 116 112 112 120 The abrasive flow sensormay be calibrated to accurately measure the flow rate and output a signal to the controller. Various abrasive types can be saved into the memory of the controllerand can be selected to match the abrasive media being used in the system. The abrasive flow sensoris positioned on the blast hoseand is in communication with the controller. The controlleris configured to compare the actual abrasive flow rate measured by the abrasive flow sensorwith a predetermined optimum flow rate range based on the predetermined conditions such as nozzle size and abrasive type combination. The methodology used was as follows:

For example, the Inventors have determined optimal abrasive flow rates as shown in Table 1 for GMA Garnet Speedblast abrasive (https://www.gmagarnet.com/en-au/abrasive-blasting/speedblast)

TABLE 1 Example Optimal Abrasive Flow Rates Optimal Abrasive Hose Nozzle Abrasive flow Type Pressure size rate range First time use GMA 100 psi No. 6 278 kg/hr +/− 5% Garnet - Speedblast First time use GMA 100 psi No. 7 381 kg/hr +/− 5% Garnet - Speedblast First time use GMA 100 psi No. 8 446 kg/hr +/− 5% Garnet - Speedblast

The optimal abrasive flow rates shown in Table 1 above are valid at standard atmospheric conditions of sea level pressure at 25 degrees C. For example, the optimal abrasive flow rate range for Nozzle size No. 6 for the pressure and abrasive type specified in Table 1 extends from a lower limit of (278-5% of 278) kg/hr to an upper limit of (278+5% of 278) kg/hr, i.e. from 264 kg/hr to 292 kg/hr. Different optimal flow rates will be relevant for different atmospheric conditions. The optimal abrasive flow rates shown in Table 1 will change depending on surface type and coating thickness. It will be realised that other optimal abrasive flow rates for different combinations of nozzle size, hose pressure and abrasive type can be determined through the systematic testing method that has previously been described.

2 FIG.A 130 126 132 112 As mentioned above one or more sensors are provided to accurately measure a plurality of system operating parameters such as air pressure, temperature, humidity, and abrasive flow rate. The arrangement shown inincludes a single sensorthat measures air flow, air pressure and temperature in the pusher line. It will be understood that multiple sensors may also be used. A dew point sensormeasures dew point of incoming air. The controlleris configured to receive data from the sensors and to process the data into operator usable information.

118 112 112 114 112 The data may be displayed on a user interface display screen, which may be positioned directly on the controller, or alternatively, may be positioned remotely from the controllerfor convenient access. The data is used to monitor and/or control system parameters such as air pressure and abrasive flow rate to maintain a predetermined abrasive flow rate. For example, if air pressure is out of range an alarm is triggered, and if flow rate is out of range it is adjusted via the abrasive metering valve. The controllercan be positioned at any convenient location and preferably inside an IP66 rated ingress protection control system enclosure (dust tight & protection from high pressure jets).

5 5 5 FIGS.A,B, andC 2 4 FIGS.- 5 5 5 FIGS.A,B, andC 110 112 5 A shows Auto mode—The controller is configured to optimise the use of abrasive during the blasting process by automatically controlling i.e. “adjusting” the abrasive flow rate to remain within the optimum abrasive flow rate range for the nozzle size and abrasive type combination in use. 5 B shows Semi-Auto mode—The controller is configured to adjust the abrasive usage to a flow rate set by the operator. 5 C shows Manual mode—The controller is configured to allow the operator to manually set an abrasive flow rate and simply triggers an alarm if the actual flow rate measures outside the manually set flow rate. show a detailed flow chart illustrating a method of controlling abrasive flow in a pneumatic blast pot arrangementsuch as the one shown in.show the controllerconfigured to operate in three modes.

8 9 FIGS.and 112 In Auto mode the operator selects a nozzle size and abrasive type using the user interface display screen as shown in, and the controllerdetermines the abrasive flow rate based on a predetermined optimal range appropriate for the selected nozzle size and abrasive type. In semi-auto and manual mode, the predetermined abrasive flow rate is set by the operator.

120 112 In all three modes once blasting has commenced the abrasive flow rate sensormeasures the actual flow rate of the abrasive material and sends a signal to the controller.

112 112 114 114 114 114 112 114 114 114 In auto mode the controllercompares the actual flow rate with the predetermined optimum flow rate range based on the selected nozzle size and abrasive type combination. If the actual flow rate sensed is lower than the lower limit of the predetermined optimum flow rate range for the selected nozzle size and abrasive type combination, the controlleris configured to signal an actuator attached to the abrasive metering valveto actuate and open the abrasive metering valvea predetermined amount to allow more abrasive to flow through the abrasive metering valvethereby increasing the flow rate of abrasive. The amount the abrasive metering valveopens is based on the differential between the actual flow rate and the predetermined optimum flow rate. Likewise, if the measured, or actual flow rate is higher than the higher limit of the predetermined optimum flow rate range, the controlleris configured to signal the actuator attached to the abrasive metering valveto actuate and close the abrasive metering valvea predetermined amount to allow less abrasive to flow through the abrasive metering valvethereby reducing the flow rate of abrasive.

112 114 In semi-auto mode, the controllercompares the actual flow rate with the operator entered flow rate and actuates the abrasive metering valveto open or close to maintain the operator entered flow rate.

112 112 114 In manual mode, the controllercompares the actual flow rate with the operator entered flow rate, if the actual flow rate is outside the entered parameters, the controllerwill simply signal an alarm (there is no auto adjustment of the abrasive metering valve).

112 114 114 112 114 118 114 112 The abrasive metering valve is electro mechanically actuated, by inclusion of a stepper motor though in other embodiments an electro-pneumatic actuator or a hydraulic actuator may be used or some other suitable actuating arrangement. on start up the controllerwill drive the abrasive metering valveto the home position to home the valve, immediately after reaching this position, the controllerwill drive the abrasive metering valveopen a predetermined number of turns specific for the nozzle size selected on the user interface display screen. Once this position is achieved, adjustments of the abrasive metering valveare made until the optimum abrasive flow rate is achieved. The adjustment range is based on the abrasive type and nozzle size and is programmable via the controller.

The Inventors have found that it is preferable to reduce the length of time, and number of sensing cycles, required to bring the system to within the optimal abrasive flow rate. This meant that in response to large differences between the optimal abrasive flow rate and the actual flow rate being sensed the controller was configured to apply a coarse adjustment whereas when small differences were sensed the controller was configured to only apply a fine adjustment. It was found that if a coarse adjustment was not used then it could take many fine adjustment cycles to achieve the optimal flow rate—during which time the blast operator could have stopped and started blasting numerous times, the system would read non optimal abrasive flow rate for the extended time it would take to achieve the target. If a fine adjustment was not used then the system might keep “hunting” to achieve the optimum flow rate i.e. the system could overshoot and then have to adjust in the opposite direction. By configuring the controller to use fine adjustment the possibility of such hunting occurring was reduced.

The Inventors also found that it is preferable that the abrasive metering valve is closed each time an adjustment takes place.

Closing the abrasive metering valve allows easier adjustment of the valve when using a mechanical actuator to adjust the abrasive metering valve. Pressure to the control line that acts to open and close the abrasive metering valve is shut off. This allows the abrasive metering valve to slam shut due to the action of the spring on the plunger. This releases tension on the spring and allows the valve spindle to be rotated by the actuator smoothly and with less required force. Pressure is then re-applied to the control line forcing the plunger to open to the new position—i.e. if the valve was opened then the air pressure in the control line will act against a reduced spring tension and open the plunger, if the valve was closed then air pressure in the control line will act against an increased spring tension causing the plunger to not open as far and therefore reduce abrasive flow rate. For a pneumatic actuator the pressure the control line that acts to open and close the metering valve is adjusted so that a reduced pressure will allow the tension in the valve spring to close the valve slightly and an increased pressure will overcome the valve spring tension to open the valve slightly. This adjustment continues throughout blasting operations when the flow rate is sensed to be outside the target range.

The time the abrasive metering valve (AMV) remains closed while it is adjusted is important because it is preferable that the operator does not sense that the abrasive has stopped flowing. Accordingly, it is preferable to set the time the AMV remains closed long enough to allow the adjustment to take place but short enough so the operator would not feel the abrasive not flowing (or to reduce this as much as possible).

120 116 112 114 112 120 100 114 100 During the blasting process, the abrasive flow sensorcontinuously measures the rate of abrasive flow through the blast hoseand feeds it back to the controller. In Auto and semi-auto mode the process of adjusting the abrasive metering valvecontinues to repeat such that the rate of abrasive flow remains within the predetermined range of abrasive flow for the selected nozzle size and abrasive type combination. The controllerwill continuously receive the signal from the abrasive flow sensorat a predetermined frequency. This allows time for the abrasive control systemto stabilise after the abrasive metering valvehas been actuated, and a new flow rate comparison and adjustment is made. This minimises the systemhunting and continuously adjusting.

100 120 112 118 110 10 FIG. Should the systemnot be able to achieve the required abrasive flow rate for a predetermined period, or in other words, should the abrasive flow rate sensormeasure the abrasive flow rate to be outside of the predetermined flow rate for a predetermined period, the controllerwill trigger a system alarm. The alarm may be displayed on the user interface screensuch as shown in. The alarm indicates the automated process of adjusting the abrasive flow rate described above has reached its limit and there is a problem with one or more of the system inputs. For example, there may be no abrasive in the blast potor there may be a problem with the air supply. The alarm will notify the operator the abrasive flow rate is outside the predetermined optimum range and needs to be rectified.

120 100 110 116 110 116 112 122 116 122 110 116 120 114 116 2 FIG. If the flow rate measured by the abrasive flow rate sensoris too low for a predetermined period, the systemwill ‘auto choke.’ Referring to, during operation the air pressure in the blast potand the blast hoseis equal, allowing the abrasive to enter the air stream at the blast potand continue through the blast hose. One possible reason for low abrasive flow rate may be a blockage. To release the blockage the controlleris configured to send a signal, which may be referred to as a “toggle signal” to a solenoid valvewhich supplies air to the blast hose. The solenoid valvecloses and opens several times, promoting a higher pressure in the blast potthan in the blast hosewhen the solenoid valveis closed, this ‘choking’ effect forces possible blockages in the abrasive metering valveout and into the blast hose.

112 110 Advantageously, the controllermay be configured to independently monitor flow rate signals from abrasive flow rate sensors attached to a plurality of blast hoses and to independently and automatically adjust the abrasive flow rate via actuating the abrasive metering valve to any blast hose connected to the blast potin a similar way as described above.

112 118 118 8 14 FIGS.- As mentioned above the controllermay include a user interface display screensuch as shown in. The display screenmay be a touch screen to enable operators to select system parameters and view displayed messages such as operating information, warning messages and alarms. Access to the touch screen user interface may be controlled by a user login system configured to provide a number of levels of user access.

6 7 FIGS.and show schematics of a blast pot control circuit for a pneumatic deadman system and an electric deadman system respectively. Both circuit diagrams also show the system and method for controlling abrasive flow through the blast pot arrangement.

6 7 FIGS.and In, the various components and corresponding item numbers in the figures, are as set out in Table 2 below:

TABLE 2 FIGS. 6 and 7 Item Nos. Item No Component 601 Air inlet ball valve 602 Union end ball valve 603 Blowdown ball valve 604 Exhaust air muffler 605 Safety valve 606 Blast pot 607 Choke valve 608 Auto air valve 609 Abrasive metering valve 610 Abrasive cutoff valve 611 Deadman handle 612 Strainer 613 Blast control valve 614 Abrasive control valve 615 Pressure/Temp/Flow sensor 616 Dewpoint sensor 617 Pressure transducer 618 Abrasive flow sensor 619 Pressure gauge 620 Metering control valve 621 Abrasive metering actuator 710 Abrasive cut-off switch 711 Electric Deadman handle 720 Relay 722 Metering control switch

609 614 621 As described above, the abrasive metering valvemeasures the abrasive flow to the blast nozzle and signals the controller. The abrasive control valveis actuated by the abrasive metering actuatorto control the abrasive flow based on a signal received from the controller. Multiple sensors/transducers measure parameters such as pressure, temperature, and dew point.

A number of factors can cause blast hose air pressure and abrasive flow rate to fluctuate during the blasting process. When abrasive blasting is carried out in an environment where humidity is impacting the abrasive flow rate, the abrasive flow rate may become non-optimal. Advantageously, in these situations, the method described above can adjust the abrasive flow rate such that it remains within the predetermined optimum range of abrasive flow for the selected nozzle size and abrasive type combination without operator intervention.

2 2 FIGS.A andB 1 FIG. 130 128 130 112 112 130 130 112 118 24 Referring back to, blast pot inlet air pressure may be measured by air pressure sensorfitted to the blast pot inlet air pipe. The air pressure sensoris in communication with the controller, and during operation, the controllermonitors the signal from the inlet air pressure sensorand is configured to compare the actual inlet air pressure measured by the inlet air pressure sensorwith a predetermined optimal inlet pressure range. If the measured inlet pressure is lower than the predetermined optimum range for inlet pressure the controlleris configured to trigger an inlet pressure alarm and display a warning on the user interface display screen. If the measured inlet pressure is higher than the predetermined optimal inlet pressure range then a pressure relief valve (in) opens when actual pressure reaches the preset pressure.

130 132 128 112 112 130 132 112 118 Similarly, the blast pot inlet air temperature may be measured by sensorand the dew point may be measured by the dew point sensor, both fitted to the blast pot inlet air pipeand in communication with the controller. During operation, the controllermonitors the signal from the temperature sensoralong with the inlet air dew point measured by the dew point sensorand compares the actual inlet air temperature with the actual dew point of the inlet air. If the inlet temperature sensed is equal to dew point for a predetermined period, such as 10 seconds, the controlleris configured to trigger a high air moisture content alarm and display a warning on the user interface display screen, such as “High air moisture content.” Preferably, the alarm requires a reset to clear.

2 2 FIGS.A andB 124 118 124 112 112 124 126 112 118 Still referring to, pressure sensormeasures the pressure in the pusher line. The sensoris in communication with the controller. During operation, the controllermonitors the signal from the pressure sensorand is configured to compare the actual pressure in the pusher linewith a predetermined optimal pressure range. If the measured pusher line pressure is outside the predetermined optimum range the controlleris configured to trigger a hose high or low pressure alarm (depending on actual pressure in the hose) and display a warning on the user interface display screen.

100 112 112 100 The physical location of the automated blast pot systemmay be monitored by a Global Positioning System (GPS) connected to the controllerallowing the controllerto log the location of the automated abrasive control systemduring operation.

8 13 FIGS.- 8 FIG. 9 FIG. 118 100 118 show various screen shots of the user interface display screen. The automated abrasive control systemis configured to enable the operator to select various system parameters and inputs relevant to optimising the blasting process via the user interface display screen. System parameters may include blast nozzle (), abrasive type (), optimum inlet pressure range, optimum outlet pressure range, a predetermined abrasive type and blast nozzle combination to apply a predetermined optimum abrasive flow rate range, the duration each blast hose has been in operation and system alarm history.

118 1. reset system alarms; 2. reset information totalisers; 3. setup user security; 4. perform system admin tasks; and 5. set equipment maintenance intervals. The operator may also do the following via the user interface display screen:

Abrasive type flow rate calibration data to the flow sensor may be input by a technician and is locked to prevent unauthorised changes.

100 118 instantaneous parameter values displayed in numerical format; parameter values totalled over a period displayed in numerical format; calculated instantaneous parameter values in numerical format; and parameter trend information displayed in chart format. The automated abrasive control systemis configured to log and record, at selectable intervals, system operational data from the various connected sensors and to calculate and display on the user interface display screenvarious informative instantaneous and calculated trend information in various formats such as:

System parameters can be displayed in both metric and imperial standard units.

118 1. instantaneous blast pot inlet air pressure; 2. instantaneous blast pot inlet air temperature; 3. instantaneous blast pot inlet air dew point; 4. instantaneous pusher line air pressure for each and any connected hose; 5. instantaneous blast hose abrasive flow rate for each and any connected hose; 6. blast pot inlet air pressure trend; 7. blast pot inlet air temperature trend; 8. blast pot inlet air dew point trend; 9. blast pot outlet hose air pressure trend for each and any connected hose; 10. blast pot outlet hose abrasive flow rate trend for each connected hose; 11. totalised abrasive usage—daily and cumulative since last reset; 12. date and time; 13. type of abrasive media selected for use; 14. size of the abrasive nozzle selected for use; 15. geographical location of the automated blast pot system; 16. low abrasive flow alarm—by hose; 17. high abrasive flow alarm—by hose; 18. low inlet pressure alarm; 19. low outlet pressure alarm—by hose; 20. temperature equal to dew point—high air moisture content alarm; and 21. blast hose active time for each and any blast hose connected including daily and cumulative since last reset. This displays when a blast hose is active and records the duration the blast hose has been active over a timeframe selectable by the user. A blast host is considered to be active for the period of time when the pressure in the control line is recorded as being above a pre-set minimum pressure. This functionality creates information enabling the following actual system parameters and performance to be displayed and monitored on the user interface display screen:

100 112 The automated abrasive control systemrecords the system parameter and performance information on an internal memory device within the controller. Information stored on the memory device can be accessed locally from a compatible device and downloaded to a selected location on the device.

100 100 100 100 118 100 A communication modem is connectable to the automated abrasive control systemand when energised and connected to a compatible mobile telecommunications network, information generated by the automated abrasive control systemcan be exchanged between the automated abrasive control systemand a remotely connected device. Information generated by the automated abrasive control systemand displayed on the user interface display screencan be viewed by operators from a remote location by connecting a compatible fixed or mobile device to the automated abrasive control systemvia the connected communication modem.

Operators can remotely log in as a specific user (operator, supervisor or engineer) and select and view the user interface display screens, select and view and download various saved and real time information and change various parameters (e.g. alarm max. min thresholds) available based on the security level of the logged in role.

100 118 A cloud hosted user accessible dashboard is also developed and configured to display system parameter and performance information. Information generated by the automated abrasive control systemis uploaded at near real time intervals to a remotely hosted database and the dashboard application is programmed to calculate and display similar information to that available to be viewed on the user interface display screen. Users, or operators, are provided with an access code to gain access to the dashboard and can connect and view the dashboard remotely via network connected compatible devices.

100 An uninterruptable power supply with an internal battery is also connected to the automated abrasive control systemto provide system power for a predetermined time after the control panel is switched off. This provides power for a timeframe sufficient for the operating data stored in the local system memory to be uploaded to the remotely hosted database via the communication network.

In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. This to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.